1) "VESES HA'CHODESH" -- EXPECTING TO SEE BLOOD ON A PARTICULAR DAY OF THE MONTH
OPINIONS: The Gemara discusses a dispute between Rav and Shmuel about how a woman establishes a monthly-interval Veses. The fact that the Gemara discusses establishing a Veses in the case of a woman who bleeds on the fifteenth day of one month, on the sixteenth of the next month, and on the seventeenth of the third month, implies that there is some link between the days of the month and her bleeding.
While it is clear that certain physical signs (such as cramping, trembling, sneezing) can indicate the onset of menstruation, how can a calendar date, such as the day of the month, be linked to bleeding?
(a) The RAMBAN writes that it is not possible that a woman's bleeding is linked to the day of the month. "Does the Shofar [that announces when the new month begins] cause her to bleed? Does the constellation of that month cause her to bleed?" The Ramban infers from the fact that the RAMBAM makes no mention of this Veses that he also maintains that it is not possible for a Veses to be linked to the day of the month.
(b) The RE'AH (Bedek ha'Bayis 7:3) also writes that it is not possible or logical for a Veses to be established according to the day of the month. However, it could be established based on the phase of the moon (as calculated from the Molad), since there is a relationship between the phase of the moon and a woman's menstruation. The Ramban also mentions the idea that a full moon may influence the menstrual cycle.
RAV YEHONASAN EIBSHITZ (Pleisi 189) questions this assertion. If a woman's cycle is related to the phases of the moon, then determining her Veses should require complex calculations based on the real Molad of the exact location in which she lives; it cannot be based on the standardized Molad, which is based on the calculation of the Molad in Cairo.
(c) The RASHBA (Toras ha'Bayis 7:3) maintains that there certainly is a monthly Veses based on the day of the month. He justifies this assertion based on the Yerushalmi (Kesuvos 1:2) which states that if a girl reaches the age of three in Nisan and Beis Din decides to add a second Adar before Nisan begins, the girl's physical nature will be affected by their decision. If she is raped during the second Adar, her Besulim will regenerate; if she is raped during Nisan, they will not.
(d) TOSFOS (DH Itmar, and as cited by the Ramban) says that not only can her Veses be linked to a specific day of the month, but it can also be linked to a specific day of the week. (That is, if she bled consistently on three Sundays, Sunday will become her Veses; see Chart.)
HALACHAH: The Ramban (Hilchos Nidah 5:12) concludes that we should be stringent and follow the opinion of Tosfos and observe a monthly Veses as well as a weekly one. This is also the ruling of the SHULCHAN ARUCH (YD 189:3).

64b----------------------------------------64b

2) THE RULING OF MINYAMIN
QUESTIONS: The Gemara quotes Rav who said that when a Bogeres gets married she is permitted to her husband for the entire first night, even if she experiences bleeding after the first Be'ilah; we assume that the blood was Dam Besulim and not Dam Nidah. RASHI (DH Bogeres) explains that even Beis Hillel in the Mishnah agrees with this ruling. Beis Hillel maintains that a girl who is old enough to see Dam Nidah ("Higi'a Zemanah Lir'os"; see RAN in Shevuos, 4a of the pages of the Rif, DH v'Higi'a, and TIFERES YISRAEL #1) is permitted to her husband for the first four nights, because we assume that any bleeding during that time comes from her Besulim and not from Dam Nidah. However, this refers only to a Na'arah (between the ages of twelve and twelve and a half), and not to a Bogeres (over the age of twelve and a half). Beis Hillel agrees that a Bogeres is permitted only for the first night.
The Gemara says that a Bogeres is permitted to her husband for all of the first night only when she has not seen Dam Nidah before. If she has seen Dam Nidah before, then she is permitted only for the first Be'ilah (Be'ilas Mitzvah) and not more.
(a) The Gemara here seems to contradict the Gemara later (65b) which says that both Rav and Shmuel rule that the new husband is permitted to perform only the Be'ilas Mitzvah and must then separate from his wife until she becomes Tahor from a presumed flow of Dam Nidah. Rashi there (DH Halachah) writes that whether or not she has reached the age at which she is fit to see Dam Nidah, only the first Be'ilah is permitted!
(b) The Gemara later (65a) also seems to contradict the opinion of Rav (65b). The Gemara (65a) states that Minyamin Saksena'ah, while traveling to the city where Shmuel was the leading Halachic authority, intended to rule in accordance with Rav even in a case in which the young woman had seen blood before the wedding. Minyamin said that Rav did not distinguish between a young woman who had seen blood before and one who had not seen blood.
How could Minyamin, who was a close disciple of Rav, say that there is no difference between a young woman who had seen blood before and one who had not seen blood? The Gemara earlier explicitly states that if she had seen blood, she is permitted to her husband only for the Be'ilas Mitzvah!
ANSWERS:
(a) The CHIDUSHEI HA'RASHBA (65b) answers that Rav here (64b) is merely explaining the law of the Mishnah. In practice, however, Rav agrees with Raboseinu cited in the Beraisa (65b) who ruled that after the Be'ilas Mitzvah the husband must separate from his wife until she becomes Tahor.
(b) The Chidushei ha'Rashba (64b) writes that the statement that the Bogeres is permitted for the entire night only when she has not previously seen Dam Nidah was not actually said by Rav. Rather, it is the Gemara's addition to Rav's ruling. Rav himself maintains that she is permitted for all of the first night. The Rashba writes that Rav derives this ruling from the end of the Mishnah, which states that if the girl had reached the age at which she would expect to see blood, and indeed she saw blood while still in her father's house, according to Beis Hillel she is permitted for the entire night. Rav maintains that there is no difference between the law of "Higi'a Zemanah Lir'os" (i.e. twelve years and one day) who saw blood, and a Bogeres (twelve and a half years and up) who saw blood. From the fact that the Mishnah does not discuss a Bogeres, Rav infers that the law of a Bogeres indeed is identical to the law of "Higi'a Zemanah Lir'os," because, otherwise, the Mishnah should have explained the law of a Bogeres.
The Rashba writes that Minyamin was a student of Rav and was an expert in his teacher's Halachic opinions. Therefore, we may rely on his statement that Rav made no distinction between a young woman who had seen blood before and one who had not seen blood, and we may conclude that this indeed was Rav's opinion. The Rashba writes that this is the reason why the Gemara (65a) says that after Minyamin died, Shmuel applied the verse, "No evil shall happen to the righteous" (Mishlei 12:21), to Rav, but he did not say anything about Minyamin. Minyamin did not deserve criticism because he indeed said only what he had heard from Rav. (See footnote 5 to Chidushei ha'Rashba, which asserts that Minyamin's death was not a punishment at all.) However, the Gemara disagrees with Rav's ruling, and the Halachah does not follow Rav. Nevertheless, Rav possessed special Divine assistance which prevented his student, Minyamin, from making a mistake through his words. (The Rashba writes that the Gemara here is similar to the Gemara in Chulin (59a) and Yevamos (121a) which also relate accounts in which Rav possessed special Divine assistance so that no mistakes would be made because of what he said.)
(See TOSFOS later (65a, DH Davar) who disagrees with the Rashba and writes that Minyamin intended to make a ruling which Rav had never said, and therefore Shmuel criticized him. Tosfos asserts that Rav himself maintained that if the young woman had previously seen blood, she is permitted only for the Be'ilas Mitzvah, and thus it is not necessary to say that this is the Gemara's addition to Rav's words, but rather it was Rav himself who said these words. See also Rashba (65b), who writes that although Rav's final ruling was in accordance with the view of Raboseinu (as mentioned above), who said that only the Be'ilas Mitzvah is permitted in any situation, while Minyamin intended to permit even a Bogeres for all of the night, Shmuel did not criticize him for this ruling because this was the ruling of the Mishnah according to Rav (even though it was not Rav's ruling in practice). Shmuel would not have criticized someone who intended to rule according to the Mishnah.) (D. BLOOM)

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